Mesa Boogie design complaints

[rabies]

yeah, this board is badass for me especially. I have zero tech experience with amps other than replacing tubes, biasing with bias rite and replacing the power tranny for a Crate tube amp a while back (and it worked!)

I'd love to be able to build the simple amp in Dave Hunter's book (I love that book!)

http://www.amazon.com/Guitar-Amp-Han...1216507&sr=8-1

Yeah Enzo and others on this board make boogiebabies (Ed?) from boogie board seem elementary and he was very helpful on that forum...

[rabies]

Like Enzo says,Mesa amps are so cold,most power tubes will not fry,particularly with those EL34's in the MKIV,have yet to see one any hotter than 15ma's and as low as 4ma's.But in my MKIIC+ and SOB,and a couple of others I have worked on, I have seen some NOS 6L6's draw close to 70% MPD,so I would still recommend checking the bias of any power tube you try,but that goes for any amp.Rabies,you know my theories on Mesa's marketing scheme from the Boogie Board,they are in the business of selling tubes as well as amps,so of course it works best for them.A lot of players dont want to be bothered thinking about bias so for them,it works too.Welcome to the board,rabies,I think you'll like it here,a lot of knowledgeable guys willing to help,and never a shortage of info.

So why/how did my brand new Stiletto Deuce II (that I later returned for a refund) end up blowing 3 power tubes in less than 2 weeks? It wasn't the spkr cable or cab b/c I used the same spkr cable and cab with a different Mesa later and it was fine. And I'm very careful about the load (4ohm to 4ohm, for example).

Mesa customer service said "it was the tubes". How can there be a bad batch of tubes that have supposedly been QC'd by robotube? very sketchy and turned me off to Mesa to a certain extent after that happened...

[rabies]

so consider this:

The bias point determines several things about a tube amplification stage. It determines the power output, amount of distortion, headroom (the size of input signal that can be applied before the output signal clips), efficiency of the stage (the amount of output signal power vs. DC input power), gain of the stage (the magnitude of the output signal for a given input signal), noise of the stage, and class of operation (class A, AB, etc.). The proper bias point is a tradeoff between all of these factors, and selecting the optimum bias point can sometimes be difficult, and it will vary depending on the amplification stage requirements.

http://www.aikenamps.com/WhatIsBiasing.htm

So what is the effect of having a low MPD (say 50-60%) in a cold-biased setup like a Mesa tube amp with hi or low cascading gain? More headroom?

It seems to me that the Hendrix, Page, etc. Marshall guys in the 60s and 70s cranked the power stage for EL34 saturation but didn't they mic the cabs back then too?

You can't crank master output to 75% and higher and mic the speaker, can you?

But their non-master volume equipped amps' sound relied on power tube saturation with the EL34's, no?

Seems to me most Mesa players nowadays (e.g. Mark IV and Recto line) don't turn up past 3 out of 10 on the output and then mic the speaker...

[rabies]

and another observation with tube amps I've used:

after noon on the power stage output, it doesn't get louder decibel-wise. I've read with Mesa's, when the amp is scoped with an oscilloscope, that you basically just get more power tube distortion when you turn the output past 50%...

this seems to be true with my JMP1/monobloc rig as well...

[Enzo]

You can always mic a speaker. They record concert loudness live don't they? You can mic a jet aircraft engine. In such applications all you need is a mic that can handle whatever loudness levels you have. The demands on a kick drum mic I'd say would be much greater than on a guitar speaker mic. Cranking the amp is about getting a particular sound or tone. The mic part is there to send the signal elsewhere. A triple stack of 100w Marshalls is pretty loud when you stand within a guitar cord length of it, but it certainly doesn't fill a baseball stadium. So the PA system amplifies the sound and spreads it around . And some cabs are very beamy, so right in front it is loud, but a few degres off to the side and you lose it. Mic it through the PA and everyone can hear. A mic on the speaker evens out the mix.

Power tube distortion is only partly connected to master volume setting. Power tubes only distort when they are cranking their full power output and are pushed further. You won;t get power tube distortion in a 100 watt amp when it is making 50 watts. The setting of the master volume is not a power control. It does control what is sent to the power amp, but if you turn down the MV, and then turn up the guitar, you wind up just as loud as before - and that means the power output is the same too. Oh there may be differences in tone and nuance, but that is beside the point.

If someone doesn;t care about power tube distortion, and wants to keep stage volume down, then they might turn the amp down and mic it for loudness in the house seats. SOmeone else could leave the mic in the box and crank the amp to the moon. But the decision to mic or not is not a matter of can't above some setting.

And as to three tubes failing in an amp in a short period, I'd have to agree with Mesa, it was probably the tubes. Could also be an amp problem, maybe a cracked solder joint causing a loss of bias. I tend not to think it is some systematic design shortcoming or all the Stilettos would be doing this.

QC is a test of something working, but it is not a guarantee it won;t fail. If you have 100 tubes to test, you can have a machine do it or an intern do it by hand, doesn't matter which really. SOme tubes will be OK, and some will be bad. Throw the bad ones out. Now you have a batch of all 100% tested good tubes.

That doesn't tell us about any tubes that are about to fail next week. That doesn;t tell us that the tubes will not bounce over railroad tracks at 50 miles per hour in the back of a semi all the way across the country. Testing weeds out bad ones, and we have more confidence in the remaining tubes than if we just shipped every tube we had. BUt any tube can fail any time. Ever watch people handle cargo and parcel freight? They don;t play soccer with the boxes, but they don;t sit them down one by one with raised pinky either. Drop a box of new tested tubes on the floor, and you will have a higher failure rate in the tubes from that box.

And even tubes that are not mistreated can have variations in quality. One batch of tubes might have a great reliability . The next batch might test out OK, but then after the tubes find their way into service, they start to get reports that many of them are failing after a week or so. WHy might this be so? Tubes are pieces of metal bent and shaped and welded. The constant motion and wear in the machinery that does that can allow tolerances to drift. Every so often they have to tighten up and recalibrate such things. But a batch of tubes made near the end of that cycle might be a little looser inside, the welds maybe not quite so robust, and so on.

[ETR]

The stone cold bias that Mesa sets up thier amps for is the very reason no one likes the sound of them with the master up past 3. I've put adjustable bias pots in them and you can actually get a decent clean or power tube sat sound.

[stokes]

The stone cold bias that Mesa sets up thier amps for is the very reason no one likes the sound of them with the master up past 3. I've put adjustable bias pots in them and you can actually get a decent clean or power tube sat sound.

I think a lot of people have a misconception of what a master volume actually does.When you max your MV you are efectively taking the volume control out of the circuit,so you have the effect of your entire pre-amp signal getting to the out put stage.If you look at a non-master Fender amp,there is a resistor from the signal path to ground in front of each grid.This is essential for the tube to operate properly.A larger resistor will attenuate less signal-a smaller resistor will attenuate more of the signal.If you make this resistor adjustable,you have a master volume control,assuming you have a volume control in an earlier stage.This earlier volume control is basically your "gain" control.In a Mesa amp,such as the MK series amps,the pre-amp generates a ton of overdrive which slams the hell out of the power section.I am a proponent of using an adjustable bias control in these amps,but you have to go easy on how hot you bias your power tubes if you plan to use the pre-amp maxed in the lead or hi-gain stage.I find it will cause some pretty ratty distortion in lead mode if you bias them hot enough to get good power tube saturation with the clean or rythm channel.I mainly use my clean channel on the Boogies I own,but to counter this effect somewhat in lead mode a couple of 5751's in the right place will ease things up some.This is usually unacceptable to guys who want that metal distortion.

[rabies]

I think a lot of people have a misconception of what a master volume actually does.When you max your MV you are efectively taking the volume control out of the circuit,so you have the effect of your entire pre-amp signal getting to the out put stage.If you look at a non-master Fender amp,there is a resistor from the signal path to ground in front of each grid.This is essential for the tube to operate properly.A larger resistor will attenuate less signal-a smaller resistor will attenuate more of the signal.If you make this resistor adjustable,you have a master volume control,assuming you have a volume control in an earlier stage.This earlier volume control is basically your "gain" control.In a Mesa amp,such as the MK series amps,the pre-amp generates a ton of overdrive which slams the hell out of the power section.I am a proponent of using an adjustable bias control in these amps,but you have to go easy on how hot you bias your power tubes if you plan to use the pre-amp maxed in the lead or hi-gain stage.I find it will cause some pretty ratty distortion in lead mode if you bias them hot enough to get good power tube saturation with the clean or rythm channel.I mainly use my clean channel on the Boogies I own,but to counter this effect somewhat in lead mode a couple of 5751's in the right place will ease things up some.This is usually unacceptable to guys who want that metal distortion.

As far as a Mark IV is concerned, almost all those players use the lead channel (that's the main channel on that amp). So when you say you mainly use the clean channel, not sure if you're talking about a Mark I or what as the Mark II/III is very similar to the Mark IV.

I think Mesa designs their amps with the (correct) assumption that in the lead channel, most guys will have the gain up to noon or higher. So as you say, most guys slam the power section with the gain/drive from the preamp. They don't want the OT to blow and thus set the bias lower than say what a a Marshall recommends/requires for 60-70% MPD.

But essentially I am doing the same thing with the volume and gain in OD2 set to 15 in my JMP1 and crank the output to 9 oclock to noon on my JMP1 going into dual monobloc 100watts. No problems so far and I get great brutal power tube distortion as well with the EL34's.

check this out about bias on a Stiletto:

http://forum.grailtone.com/viewtopic.php?f=4&t=31708

not all settings are cold according to his bias rite readings...

[rabies]

now that I think about it. if the power tubes are not saturated in most Mesa amps due to the cold biasing, you may as well run a Mesa preamp into a SS power amp. how much power tube "tone" are you getting out of your power section in a Mesa if it's cold biased?

this is what Kurt Cobain supposedly did for the nevermind recording/tour (mesa studio 22 into crown power amps and marshall cabs) and I thought he had a pretty massive sound on that album...

maybe this is why most serious blues players use fenders or marhsalls??? i.e. would a serious blues player like SRV, Hendrix, Beck, Page consider using an amp with a cold-biased power amp section? Yeah I know Santana did but I don't like his tone/style at all anyways.

if you play metal I can understand why it may not matter as much - no dynamics and lots of gain required from preamp - (a lot of metal guys use Randall SS amps - e.g. dimebag).

[rabies]

The stone cold bias that Mesa sets up thier amps for is the very reason no one likes the sound of them with the master up past 3. I've put adjustable bias pots in them and you can actually get a decent clean or power tube sat sound.

are you talking about the master volume (per channel) or the output?

I've never head that "no one likes the sound of them with the master up past 3". I turned my ex-Mark IV to 10/10 on master and 10/10 on output (w/ the squealing of course!) and it sounded badass.

I guess I don't follow your logic of cold-biased power tubes and hi master volume equating to bad tone in boogies...

[ETR]

are you talking about the master volume (per channel) or the output?

I've never head that "no one likes the sound of them with the master up past 3". I turned my ex-Mark IV to 10/10 on master and 10/10 on output (w/ the squealing of course!) and it sounded badass.

I guess I don't follow your logic of cold-biased power tubes and hi master volume equating to bad tone in boogies...

I guess I should have just said the clean sound sucks on any amp that's turned up to at or near full power if the bias is way too cold. Sorry for any confusion.

[stokes]

"I turned my ex-Mark IV to 10/10 on master and 10/10 on output (w/ the squealing of course!) and it sounded badass."
rabies,I've said it before,at that volume you have certainly earned the name "rabies".
One day the ear doctor is gonna make a fortune on you!
As to which Boogies I am talking about,a IIC+ and an SOB.To me the term "Boogie" refers to the MK series.I saw that post on the Stilletto bias thing,but again I am refering to mainly the MK series.

[alien]

About the function I agree...but as for the sound...

The biggest problem people have with Mesa is their own ears and recording skills.

Recorded or Live through the PA the engineer must have ears. If he does not it can sound horrid. If he does you can sound Chevelle or John Petrucci(which is some of the best Modern rock guit sounds on the planet)

Its one of those big risk big reward amps. It can only be criticized in the context of who is using it.

BTW..the Mark IV that is out now is so freakin sweet I wouldn't want anything changed

[rabies]

BTW..the Mark IV that is out now is so freakin sweet I wouldn't want anything changed

Mark V: http://www.youtube.com/watch?v=ROjxB0w_4QE

I'm down with this design! 4xEL34!